Cutting devices

ABSTRACT

A cutting device for sheet material includes a first blade portion which defines a pair of opposed spaced cutting edges, a second blade portion movable between said cutting edges and operable upon such movement to shear sheet material disposed between the blade portions.

Write tates mean Couhtrie 3,738,002 June 12, 1973 CUTTlNG DEVICES [76] Inventor: Thomas Robb Coughtrie; Bryn Collen, Llanover, Abergavenny, England 22 Filed: Mar. 23, 1971 211 App]. No.: 127,326

52 us. Cl. ..30/2s1,30/25s 51 lnt.Cl B26b 13/26 58 Field oiSearch ..30/25l,258,184,

[56] References Cited UNITED STATES PATENTS 2,766,526 l0/l956 Pape 30/25l 3,492,724 2/1970 Goss 30/258 FOR EIGN PATENTS OR APPLICATIONS 833,716 4/1960 Great Britain 30/258 Primary Examiner-Granville Y. Custer, Jr. Assistant Examiner-J. C. Peters Attorneyl-lolman & Stern [57] ABSTRACT A cutting device for sheet material includes a first blade portion which defines a pair of opposed spaced cutting edges, a second blade portion movable between said cutting edges and operable upon such movement to shear sheet material disposed between the blade portions.

5 Claims, 3 Drawing Figures PAIENIED JUM 2 I973 mmTmn currruo DEVICES This invention relates to cutting devices and more particularly to cutting devices for use when cutting sheet material.

The object of the invention is to provide such a device in a simple and convenient form.

A cutting device in accordance with the invention comprises in combination, a first blade portion which defines a pair of opposed cutting edges spaced by a gap, a second blade portion which extends through said gap and which is movably mounted relative to said first blade portion, said first blade portion defining a substantially flat surface for engagement with the surface of a sheet of material to be out, said second blade portion extending beyond said substantially flat surface and having a shaped leading edge portion whereby material sandwiched between the flat surface and the leading edge portion of the first and second blade portions respectively will be severed upon movement of the blade portions relative to each other, means for supporting the blade portions and further means operable to effect relative movement of the blade portions.

In the accompanying drawings:

FIG. 1 is a side elevation of one example of a cutting device in accordance with the invention with a portion of the body removed for the sake of clarity,

FIG. 2 is a section on the line A-A of FIG. 1, and

FIG. 3 is a section on the line BB of FIG. 1.

Referring to the drawings there is provided a body portion which is formed in two parts one of the parts in FIG. I, being removed to allow an understanding of the operation of the cutting device. The parts of the body portion are secured together by means of screws engaged within apertures 11 and at these points the two parts of the body portion contact each other. The body portion includes a handle portion 12 and a head portion 13 and mounted within the head portion is a first blade portion which is constituted by a pair of inserts M which define opposed cutting edges spaced by a gap 15. The inserts 15 are mounted on pins 16 at their trailing ends and intermediate their ends an adjusting screw 1 .7 passes therethrough. As is shown in FIG. 2, the adjusting screw I7 extends through the body portion and defines shoulders which bear upon the inserts. The adjusting screw is restrained against angular movement within the body portion and the nut associated with the adjusting screw can be tightened to vary the dimension of the gap 15.

Carried by the adjusting screw 17 is a second blade portion 18 and this extends through the gap 15 and is provided with a serrated leading edge 19. At its trailing end the second blade 18 is sandwiched between a pair of links 20 and is pivotally connected thereto by means of a pin 21. The other end of the links are pivotally connected to a second handle portion 22 which is pivotally mounted by means of a pin 23 carried by the body portion. The second handle portion 22 extends through a gap defined between the two parts of body portion and furthermore, it is spring loaded by means of a spring 24 which is secured to the handle portion 22. In the position shown in FIG. I of the drawings the handle portions I2 and 22 have been moved their maximum extent towardseach other and if the handle portion 22 is released it will under the action of the spring 24 move in a .clockwise direction. During this movement the links 20 will move the second blade portion 18 in an anti-clockwise direction to its open position.

The arrangement is such that with the second blade in its open position a sheet of material placed between the inserts 14 and the serrated edge 19 of the second blade portion, will be severed as the handle portions are moved towards each other. During this movement a strip of material is cut from the sheet material, the width of the strip being substantially equal to the width of the second blade 18. Moreover, as material is cut the point at which cutting occurs moves away from the pivot defined by the screw 17 thereby increasing the cutting effort required to be exerted on the blade. The size of the gap 15 is adjusted to accord with the type of material being cut and the size of the gap is adjusted by means of the adjusting screw 17.

Such a device as described during the cutting process, will not to any appreciable extent, cause bending of the sheets of material. Furthermore, the device can be readily guided during the cutting of the material to follow a prescribed path over the material. The increased cutting effort required to be exerted on the blade is obtained in prior art devices by the operator increasing the effort applied to the handle portions. This however is tiring and reduces the ease by which the device can be guided over a prescribed path. The links are therefore arranged in such a manner that the leverage ratio between the handle 22 and the blade 18 is increased thereby maintaining the effort required by the operator substantially constant. It will be seen in FIG. 1, that the pivot axis between the links 20 and handle 22 is very close to the line interconnecting the pivot 23 and the pivot between the links 20 and the blade. When the handle portions 12 and 22 are allowed to move under the action of the spring the aforesaid pivot axis moves away from the line and the leverage ratio decreases.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A cutting device for sheet material and comprising in combination, a first blade portion which defines a pair of opposed cutting edges space by a gap, a second blade portion which extends through said gap and which is movably mounted relative to said first blade portion, said first blade portion defining a substantially flat surface for engagement with the surface of a sheet of material to be cut, said second blade portion extending beyond said substantially flat surface and having a shaped leading edge portion whereby material sandwiched between the flat surface and the leading edge portion of the first and second blade portions respectively will be severed upon movement of the blade portions, a housing carrying said first blade portion, a pivot mounting said second blade portion, said second blade portion defining an extension on the remote side of the pivot to said surface, a fixed handle portion defined by the housing, a movable handle portion, a pivot mounting said movable handle portion on the housing, a link interconnecting said movable handle portion and said second blade portion, said link being connected to said extension at a first pivot position, said link being connected to said movable handle portion at a second pivot position, said second pivot position when the second handle portion is moved to actuate the second blade portion moving towards a line intersecting the first pivot position and the pivot between the handle portions, thereby to increase the leverage between the cutting edges.

4. A cutting device as claimed in claim 3 including spring means to return the secondhandle portion and the second blade portion to their original positions, after a cutting operation.

5. A cutting device as claimed in claim 4 including an adjusting screw operable to effect variation in the separation of said cutting edges, said adjusting screw acting as the pivot for said second blade portion. 

1. A cutting device for sheet material and comprising in combination, a first blade portion which defines a pair of opposed cutting edges space by a gap, a second blade portion which extends through said gap and which is movably mounted relative to said first blade portion, said first blade portion defining a substantially flat surface for engagement with the surface of a sheet of material to be cut, said second blade portion extending beyond said substantially flat surface and having a shaped leading edge portion whereby material sandwiched between the flat surface and the leading edge portion of the first and second blade portions respectively will be severed upon movement of the blade portions, a housing carrying said first blade portion, a pivot mounting said second blade portion, said second blade portion defining an extension on the remote side of the pivot to said surface, a fixed handle portion defined by the housing, a movable handle portion, a pivot mounting said movable handle portion on the housing, a link interconnecting said movable handle portion and said second blade portion, said link being connected to said extension at a first pivot position, said link being connected to said movable handle portion at a second pivot position, said second pivot position when the second handle portion is moved to actuate the second blade portion moving towards a line intersecting the first pivot position and the pivot between the handle portions, thereby to increase the leverage between the second blade portion and the movable handle to compensate for the increased cutting effort required as the point at which the material is cut moves away from the pivot of the second blade portion.
 2. A cutting device as claimed in claim 1 in which said first blade portion is formed from two pieces of metal having inturned end portions which extend towards each other but which are spaced apaRt to define theopposed spaced cutting edges.
 3. A cutting device as claimed in claim 2 including means operable to adjust the spacing of said opposed cutting edges.
 4. A cutting device as claimed in claim 3 including spring means to return the secondhandle portion and the second blade portion to their original positions, after a cutting operation.
 5. A cutting device as claimed in claim 4 including an adjusting screw operable to effect variation in the separation of said cutting edges, said adjusting screw acting as the pivot for said second blade portion. 